Integrated fan-out (info) package structure and method

ABSTRACT

Provided is an integrated fan-out (InFO) package structure including a first die, a second die, a third die, a protective layer, and an interconnect structure. The first die has a first surface and a second surface opposite to each other. The first die has a plurality of through substrate vias (TSVs) protruding from the second surface. The second die and the third die are bonded on the first surface of the first die. The protective layer laterally surrounds protrusions of the plurality of TSVs that protrude from the second surface. The interconnect structure are disposed on the protective layer and electrically connected to the plurality of TSVs. The interconnect structure includes a polymer layer covering the protective layer.

BACKGROUND

The semiconductor industry has experienced rapid growth due tocontinuous improvements in the integration density of various electroniccomponents (i.e., transistors, diodes, resistors, capacitors, etc.). Forthe most part, this improvement in integration density has come fromcontinuous reductions in minimum feature size, which allows more of thesmaller components to be integrated into a given area. These smallerelectronic components also demand smaller packages that utilize lessarea than previous packages. Some smaller types of packages forsemiconductor components include quad flat packages (QFPs), pin gridarray (PGA) packages, ball grid array (BGA) packages, flip chips (FC),three-dimensional integrated circuits (3DICs), wafer level packages(WLPs), and package on package (PoP) devices and so on.

Currently, integrated fan-out packages are becoming increasingly popularfor their compactness.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1A to FIG. 1D are schematic cross-sectional views illustrating aprocess flow for fabricating a package in accordance with someembodiments of the present disclosure.

FIG. 2A to FIG. 2D are schematic top views of the structure illustratedin FIG. 1A to FIG. 1D.

FIG. 3A and FIG. 3B are various cross-sectional views of a die stackstructure of FIG. 1B.

FIG. 4A to FIG. 4E are schematic cross-sectional views illustrating aprocess flow for fabricating a package in accordance with someembodiments of the present disclosure.

FIG. 5A to FIG. 5E are schematic cross-sectional views illustrating aprocess flow for fabricating an integrated fan-out (InFO) packagestructure in accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Other features and processes may also be included. For example, testingstructures may be included to aid in the verification testing of the 3Dpackaging or 3DIC devices. The testing structures may include, forexample, test pads formed in a redistribution layer or on a substratethat allows the testing of the 3D packaging or 3DIC, the use of probesand/or probe cards, and the like. The verification testing may beperformed on intermediate structures as well as the final structure.Additionally, the structures and methods disclosed herein may be used inconjunction with testing methodologies that incorporate intermediateverification of known good dies to increase the yield and decreasecosts.

FIG. 1A to FIG. 1D are schematic cross-sectional views illustrating aprocess flow for fabricating a package in accordance with someembodiments of the present disclosure. FIG. 2A to FIG. 2D are schematictop views of the structure illustrated in FIG. 1A to FIG. 1D. FIG. 3Aand FIG. 3B are various cross-sectional views of a die stack structureof FIG. 1B. FIG. 4A to FIG. 4E are schematic cross-sectional viewsillustrating a process flow for fabricating a package in accordance withsome embodiments of the present disclosure

Referring to FIG. 1A and FIG. 2A, a first die 110 having a first surface110 a and a second surface 110 b opposite to each other is provided. Indetail, the first die 110 includes a substrate 112 and a plurality ofthrough substrate vias (TSVs) 114. The TSVs 114 are exposed by the firstsurface 110 a and covered by the second surface 110 b. In other words,the TSVs 114 partially embedded in the substrate 112 are not exposed atthe second surface 110 b.

In the present embodiment, the first die 110 is a wafer, such as asilicon wafer or a silicon interposer, as shown in FIG. 2A. In someembodiments, the first die 110 may be a logic die (e.g., centralprocessing unit, mobile application processor, ASIC, GPU, FPGA,microcontroller, etc.), a memory die (e.g., dynamic random access memory(DRAM) die, a Wide I/O die, a M-RAM die, a R-RAM die, a NAND die, astatic random access memory (SRAM) die, etc.), a memory cube (e.g., HBM,HMC, etc.), a high data rate transceiver die, a I/O interface die, a IPDdie (e.g., integrated passives device), a power management die (e.g.,power management integrated circuit (PMIC) die), a radio frequency (RF)die, a sensor die, a micro-electro-mechanical-system (MEMS) die, signalprocessing dies (e.g., digital signal processing (DSP) die), a front-enddie (e.g., analog front-end (AFE) dies), a monolithic 3D heterogeneouschiplet stacking die, the like, or a combination thereof.

Before the intermediate step illustrated in FIG. 1A, the first die 110may be processed according to applicable manufacturing processes to formintegrated circuits in the first die 110. For example, the first die 110includes the substrate 112, such as silicon, doped or undoped, or anactive layer of a semiconductor-on-insulator (SOI) substrate. Thesubstrate 112 may include other semiconductor material, such asgermanium; a compound semiconductor including silicon carbide, galliumarsenic, gallium phosphide, indium phosphide, indium arsenide, and/orindium antimonide; an alloy semiconductor including SiGe, GaAsP, AlInAs,AlGaAs, GaInAs, GaInP, and/or GaInAsP; or combinations thereof. Othersubstrates, such as multi-layered or gradient substrates, may also beused. Devices, such as transistors, diodes, capacitors, resistors, etc.,may be formed in and/or on the substrate 112 and may be interconnectedby interconnect structures formed by, for example, metallizationpatterns in one or more dielectric layers on the substrate 112 to forman integrated circuit. The interconnect structures are formed usingdamascene and/or dual-damascene process, in some embodiments. The TSVs114 may penetrate through the substrate 112 to electrically connect tothe interconnect structures.

Referring to FIG. 1B and FIG. 2B, a second die 120 and a third die 130are provided. In some embodiments, the second die 120 and the third die130 may be a logic die (e.g., central processing unit, mobileapplication processor, ASIC, GPU, FPGA, microcontroller, etc.), a memorydie (e.g., dynamic random access memory (DRAM) die, a Wide I/O die, aM-RAM die, a R-RAM die, a NAND die, a static random access memory (SRAM)die, etc.), a memory cube (e.g., HBM, HMC, etc.), a high data ratetransceiver die, a I/O interface die, a IPD die (e.g., integratedpassives device), a power management die (e.g., power managementintegrated circuit (PMIC) die), a radio frequency (RF) die, a sensordie, a micro-electro-mechanical-system (MEMS) die, signal processingdies (e.g., digital signal processing (DSP) die), a front-end die (e.g.,analog front-end (AFE) dies), a monolithic 3D heterogeneous chipletstacking die, the like, or a combination thereof. In the presentembodiment, the first die 110, the second die 120, and the third die 130have different functions or the same function. For example, the firstdie 110 may be a logic die with analog IP function, the second die 120may be another logic die with GPU function, and the third die 130 may bea memory die with wide I/O function.

As shown in FIG. 1B, the second die 120 and the third die 130 are bondedon the first surface 110 a of the first die 110. In some embodiments,the area and/or the width of the second die 120 and the third die 130 issmaller than the area and/or the width of the first die 110, as shown inFIG. 2B. After bonding the second die 120 and the third die 130 onto thefirst die 110, a die stack structure is accomplished.

In some embodiments, the die stack structure may involve at least twoconfigurations including a face-to-face configuration illustrated inFIG. 3A and a face-to-back configuration illustrated in FIG. 3B. FIG. 3Aand FIG. 3B both illustrate a region of the second die 200 bonded ontothe first die 110. Since another region of the third die 130 bonded ontothe first die 110 has similar configuration, details thereof are omittedhere. As shown in FIG. 3A, the second die 120 may include a substrate122 and a bonding structure 125 on the substrate 122. The bondingstructure 125 may include a bonding dielectric layer 124 and a bondingmetal layer 126 embedded in the bonding dielectric layer 124. Thebonding metal layer 126 is exposed by the bonding dielectric layer 124.The second die 120 is turned upside down and mounted onto the first die110. That is, an active surface 120 a of the second die 120 faces towardthe first surface 110 a of the first die 110, and the bonding structure125 is disposed between the substrate 122 and the first die 110.Thereafter, the second die 120 and the first die 110 are directly bondedtogether to form the die stack structure. The second die 120 areelectrically connected to the first die 110 via the bonding structure125 and the TSVs 114.

In some embodiments, before the second die 120 is bonded to the firstdie 110, the bonding metal layer 126 is aligned with the TSVs 114. Insome embodiments, the alignment of the bonding metal layer 126 and theTSVs 114 may be achieved by using an optical sensing method. After thealignment is achieved, the bonding metal layer 126 and the TSVs 114 arebonded together by a direct bonding. The bonding metal layer 126 and theTSVs 114 are directly bonded together by the application of pressure andheat. It is understood that the direct bonding involves at least twotypes of bonding, including metal-to-metal bonding andnon-metal-to-non-metal bonding such as dielectric-to-dielectric bondingor fusion bonding. For example, as shown in FIG. 3A, a portion of thebonding metal layer 126 is bonded to the TSVs 114 by metal-to-metalbonding. On the other hand, the bonding dielectric layer 124 may bebonded to a portion of the substrate 112 at the first surface 110 a bynon-metal-to-non-metal bonding. In the case, the direct bonding may bereferred to as a hybrid bonding.

Referring to FIG. 3B, the second die 120 has a non-active surface 120 bfaces toward the first surface 110 a of the first die 110. Thereafter,the second die 120 and the first die 110 are bonded together via anadhesive layer 128. In some embodiments, the adhesive layer 128 may beany suitable adhesive, epoxy, die attach film (DAF), or the like.

Referring back to FIG. 1C and FIG. 2C, an encapsulant 140 is formed toencapsulate the second die 120 and the third die 130. Specifically, theformation of the encapsulant 140 is an over-molding process thatincludes following steps. First, an encapsulation material is formedover the first surface 110 a of the first die 110 to fill in gapsbetween the second die 120 and the third die 130 and further extend tocover a top surface 120 t of the second die 120 and a top surface 130 tof the third die 130. That is, the second die 120 and the third die 130are fully covered and not revealed by the encapsulation material. Insome embodiments, the encapsulation material includes a moldingcompound, a molding underfill, a resin (such as an epoxy resin), or thelike.

It should be noted that a sidewall 140 s of the encapsulant 140 isconcave from a sidewall 110 s of the first die 110. That is, the area ofthe encapsulant 140 is less than the area of the first die 110, as shownin FIG. 2C. In some embodiments, a distance between the sidewall 140 sof the encapsulant 140 and the sidewall 110 s of the first die 110 is ina range of 500 μm to 1000 μm. Since the sidewall 140 s of theencapsulant 140 is concave from the sidewall 110 s of the first die 110,a film subsequently formed is hardly formed on the sidewall 140 s of theencapsulant 140 by a conventional deposition, such as chemical vapordeposition (CVD), spin-on coating, or the like. In the case, theprotection on the sidewall 140 s of the encapsulant 140 is getting worseas the thickness of the to-be-formed film on the sidewall 140 sdecreases, thereby resulting in the peel-off defect and furthereffecting the yield. In the present embodiment, the issue can be solved,the detail shows as following paragraphs.

Referring to FIG. 1D and FIG. 2D, a carrier 150 is mounded onto theencapsulant 140 via an adhesive layer 152, such as die attach film(DAF). In some embodiments, the carrier 150 is a glass substrate, asilicon substrate, or any suitable carrier. The carrier 150 may have asidewall 150 s substantially equal to the sidewall 110 s of the firstdie 110. However, the disclosure is not limited thereto. In otherembodiments, the area of the carrier 150 may be greater than the area ofthe first die 110.

Referring to FIG. 4A, after mounting the carrier 150 onto theencapsulant 140, the structure illustrated in FIG. 1D is turned upsidedown, so that the second surface 110 b of the first die 110 facesupside. A grinding process is then performed on the second surface 110 bof the first die 110 to reveal the TSVs 114 at the second surface 110 bof the first die 110. In other words, a portion of the substrate 112 isremoved and further thinned until exposing the TSVs 114. In the case, asshown in FIG. 4A, the TSVs 114 have protrusions 114 p protruding fromthe second surface 110 b of the first die 110. In some embodiments, aheight 114 h of the protrusions 114 p is in a range of 200 nm to 4000nm. The grinding process may include a chemical mechanical polishing(CMP) process, a mechanical grinding process, or the like.

Referring to FIG. 4B, an atomic layer deposition (ALD) process isperformed to form a protective layer 160 on the sidewall 114 s of theencapsulant 114, the sidewall 110 s and the second surface 110 b of thefirst die 110, and the protrusions 114 p of the TSVs 114. In addition,the protective layer 160 further extends to cover a portion of the topsurface 150 t of the carrier 150. In some embodiments, the protectivelayer 160 includes an inorganic dielectric material, and the inorganicdielectric material includes SiN, SiO, AlO, AlN, or a combinationthereof. The protective layer 160 may have a thickness 160 t in a rangeof 50 nm to 2000 nm. It should be noted that since the ALD protectivelayer 160 has excellent uniformity and step coverage, the ALD protectivelayer 160 is able to fully cover the sidewall 114 s of the encapsulant114, thereby improving the protection of the recessed sidewall 114 s. Onthe other hand, the ALD protective layer 160 has a dense film property,thus the ALD protective layer 160 is able to block the etchant orchemical subsequently applied from damaging the encapsulant 114, andfurther protect the second die 120 and third die 130 within theencapsulant 114.

Referring to FIG. 4C, a planarization process (e.g., CMP process) isperformed to remove a portion of the protective layer 160. In the case,the top surfaces 114 t of the protrusions 114 p of the TSVs 114 arecoplanar with a top surface 162 t of a planarized protective layer 162.In some embodiments, the protective layer 162 may have a first portion162 a and a second portion 162 b. Specifically, the first portion 162 alaterally surrounds the protrusions 114 p of the TSVs 114 and has afirst thickness 162 t 1. The second portion 162 b covers the sidewall140 s of the encapsulant 140 and the sidewall 110 s of the first die110, and has a second thickness 162 t 2. Since the first portion 162 ais suffered the planarization process while the second portion 162 b isnot, the second thickness 162 t 2 is greater than the first thickness162 t 1.

Referring to FIG. 4D, a polymer layer 172 is formed on the top surfaces114 t of the protrusions 114 p and the first portion 162 a of theprotective layer 162. In some embodiments, the polymer layer 172 includepolyimide (PI), epoxy resin, acrylic resin, phenol resin,benzocyclobutene (BCB), polybenzoxazole (PBO), or any other suitablepolymer-based dielectric material. The polymer layer 172 may be formedby a suitable forming method, such as spin-on coating, CVD, or the like.In some alternative embodiments, the polymer layer 172 may include anorganic dielectric material, and the polymer layer 172 and theprotective layer 162 have different materials. For example, theprotective layer 162 is an ALD SiN layer, and the polymer layer 172 is apolyimide layer. The ALD SiN layer may have a density greater than adensity of the polyimide layer. As such, the ALD SiN layer has a thinnerthickness and a better protection for the recessed sidewall 114 s of theencapsulant 114.

After forming the polymer layer 172, the polymer layer 172 is patternedwhen the sidewall 114 s of the encapsulant 114 and the sidewall 110 s ofthe first die 110 are covered with the protective layer 162, so as toform a plurality of openings 173 in the polymer layer 172. The openings173 expose the protrusions 114 p of the TSVs 114. As shown in FIG. 4D, aconductive feature 174 is then formed in the openings 173 toelectrically connect the TSVs 114. In some embodiments, the conductivefeature 174 may include a seed layer and a conductive layer thereon. Theseed layer may be a titanium/copper composited layer, and may be formedby CVD or PVD. The conductive layer may include metal, such as copper,aluminum, nickel, titanium, a combination thereof or the like, and maybe formed by an electroplating process. In the present embodiment, theconductive feature 174 includes a plurality of metal pillars (e.g., Cupillars) respectively in the openings 173 to be in contact with the TSVs114. In some alternative embodiments, the polymer layer 172 and theconductive feature 174 constitute an interconnect structure 170 on thesecond surface 110 b of the first die 110. The conductive feature 174may be a circuit layer having a plurality of traces and vias stackedalternately. Although only single one polymer layer 172 and single oneconductive feature 174 are illustrated in FIG. 4D, the disclosure is notlimited thereto. In other embodiments, the number of the polymer layeror the conductive feature is adjusted by the need.

It should be noted that, the protective layer 162 is able to protect therecessed sidewall 114 s of the encapsulant 114 from damaging by theetchant or chemical during the patterning the polymer layer 172. In thecase, no peel-off defect is present, and no additional rework process isneeded to remove the peel-off defect due to full coverage protection,thereby improving the throughput and the reliability. In addition, sincethe recessed sidewall 114 s of the encapsulant 114 is fully covered bythe protective layer 162, it can enlarge the new material integrationwindow without worrying about chemical attack issue. Moreover, thepresent embodiment may enable a fine-pitch redistribution layer (RDL)structure due to the allowance of thinner polymer layer or thinner seedlayer.

Referring to FIG. 4D and FIG. 4E, a singulation process is performedalong the lines C, so as to form a plurality of singulated packages 10.As shown in FIG. 4E, the packages 10 includes the first die 110, thesecond die 120, the third die 130, the encapsulant 140, the protectivelayer 162, and the interconnect structure 170. The second die 120 andthe third die 130 are bonded onto the first surface 110 a of the firstdie 110. The encapsulant 140 encapsulates the second die 120 and thethird die 130. A cut sidewall 140 s′ of the encapsulant 140 is alignedwith a cut sidewall 110 s′ of the first die 110. The interconnectstructure 170 is disposed on the second surface 110 b of the first die110 and is electrically connected to the TSVs 114 in the first die 110.The protective layer 162 is sandwiched between the second surface 110 bof the first die 110 and the interconnect structure 170. The protectivelayer 162 laterally encapsulates the protrusions 114 p of the TSVs 114protruding from the second surface 110 b of the first die 110.

FIG. 5A to FIG. 5E are schematic cross-sectional views illustrating aprocess flow for fabricating an integrated fan-out (InFO) packagestructure in accordance with some embodiments of the present disclosure.

Referring to FIG. 5A, a carrier 20 is provided. In some embodiments, thecarrier 20 is a glass substrate, a silicon substrate, or any suitablecarrier. A redistribution layer (RDL) structure 30 is formed on thecarrier 20. In detail, the RDL structure 30 may include a polymer layer32 and a conductive feature 34 embedded in the polymer layer 32. Thepolymer layer 32 may be a single layer or a multilayer structure, forexample. In some embodiments, the polymer layer 32 include polyimide(PI), epoxy resin, acrylic resin, phenol resin, benzocyclobutene (BCB),polybenzoxazole (PBO), or any other suitable polymer-based dielectricmaterial. The polymer layer 32 may be formed by a suitable formingmethod, such as spin-on coating, CVD, or the like. In some embodiments,the conductive feature 34 includes a plurality of traces and vias (notshown) stacked alternately. The conductive feature 34 is formed byfollowing steps including forming a seed layer (not shown) on thepolymer layer 32 by a CVD process or a PVD process (e.g., sputtering),forming a photoresist pattern (not shown) with a plurality of openingson the seed layer, forming a conductive material (not shown) in theopenings by a plating process, and removing the photoresist pattern andthe seed layer covered by the photoresist pattern. In the case, theconductive feature 34 may include the conductive material and underlyingseed layer. In some embodiments, the conductive feature 34 may includemetal, such as copper, aluminum, nickel, titanium, a combination thereofor the like.

Although only one RDL structure 30 is illustrated in FIG. 5A, theembodiments of the present invention are not limited thereto. In someembodiments, one or more RDL structures are formed on the carrier 20.That is, one or more polymer layers and conductive features formed inthe one or more polymer layers are included in the RDL structure 20.However, the layout or the arrangement of the RDL structures is notlimited by the embodiments described herein.

Referring to FIG. 5B, after the RDL structure 30 is formed, a pluralityof through insulator vias (TIVs) 35 are formed on and electricallyconnected to the RDL structure 30. In some embodiments, the TIVs 35 areformed by photolithography, plating, and photoresist stripping process.For example, the TIVs 35 include copper posts. The TIVs 35 may be formedby following steps including forming a seed layer (not shown) on the RDLstructure 30 by a CVD process or a PVD process (e.g., sputtering),forming a photoresist pattern (not shown) with a plurality of openingson the seed layer, forming a conductive material (not shown) in theopenings by a plating process, and removing the photoresist pattern andthe seed layer covered by the photoresist pattern. In the case, the TIVs35 may include the conductive material and underlying seed layer. Insome alternative embodiments, the TIVs 35 are obtained by themanufacturer may be mounted on the RDL structure 30.

Referring to FIG. 5C, after the TIVs 35 are formed, the package 10 (FIG.4E) is de-mounted from the carrier 150. Next, the package 10 and afourth die 40 are picked and placed on the RDL structure 30. The package10 and the fourth die 40 are disposed in parallel, and surrounded by theTIVs 35. In the case, the package 10 may have the second surface 110 bfacing upside, and the fourth die 40 may include a plurality of contacts42 facing upside. In some embodiments, the fourth die 40 may be a logicdie (e.g., central processing unit, mobile application processor, ASIC,GPU, FPGA, microcontroller, etc.), a memory die (e.g., dynamic randomaccess memory (DRAM) die, a Wide I/O die, a M-RAM die, a R-RAM die, aNAND die, a static random access memory (SRAM) die, etc.), a memory cube(e.g., HBM, HMC, etc.), a high data rate transceiver die, a I/Ointerface die, a IPD die (e.g., integrated passives device), a powermanagement die (e.g., power management integrated circuit (PMIC) die), aradio frequency (RF) die, a sensor die, amicro-electro-mechanical-system (MEMS) die, signal processing dies(e.g., digital signal processing (DSP) die), a front-end die (e.g.,analog front-end (AFE) dies), a monolithic 3D heterogeneous chipletstacking die, the like, or a combination thereof. The first, second,third, and fourth dies 110, 120, 130, and 40 may different functions orthe same function. In some embodiments, the height of the package 10 issubstantially the same as the height of the fourth die 40, and is lowerthan the height of the TIVs 35.

Referring to FIG. 5D, an encapsulant 50 is formed to laterallyencapsulate the package 10, the fourth die 40, and the TIVs 35. In someembodiments, the encapsulant 50 includes a molding compound, a moldingunderfill, a resin (such as an epoxy resin), or a combination thereof,or the like. The encapsulant 50 may be formed by a sequence of anover-molding process and a planarizing process. For example, anencapsulation material (not shown) is formed over the RDL structure 30to fill in the gaps between the package 10, the fourth die 40, and theTIVs 35 and encapsulate the package 10, the fourth die 40, and the TIVs35. In addition, the encapsulation material further covers the topsurfaces of the package 10, fourth die 40, and TIVs 35. The planarizingprocess is performed on the encapsulation material until the top surface174 t of the conductive feature 174, the top surfaces 42 t of thecontacts 42, and the top surfaces 35 t of the TIVs 35 are exposed. Inthe case, the top surface 174 t of the conductive feature 174, the topsurfaces 42 t of the contacts 42, the top surfaces 35 t of the TIVs 35,and a top surface 50 t of the encapsulant 50 are coplanar afterperforming the planarizing process. In some embodiments, the planarizingprocess includes a mechanical grinding process and/or a chemicalmechanical polishing (CMP) process.

Referring to FIG. 5E, a RDL structure 60 is formed on and electricallyconnected to the package 10, the fourth die 40, and the TIVs 35. In someembodiments, the RDL structure 60 includes a plurality of polymer layersPM1, PM2, PM3 and PM4 and a plurality of redistribution layers RDL1,RDL2, RDL3 and RDL4 stacked alternately. The number of the polymerlayers or the redistribution layers is not limited by the disclosure.

In detail, the redistribution layer RDL1 penetrates through the polymerlayer PM1 and is electrically connected to the conductive feature 174 ofthe package 10, the contacts 42 of the fourth die 40, and the TIVs 35.The redistribution layer RDL2 penetrates through the polymer layer PM2and is electrically connected to the redistribution layer RDL1. Theredistribution layer RDL3 penetrates through the polymer layer PM3 andis electrically connected to the redistribution layer RDL2. Theredistribution layer RDL4 penetrates through the polymer layer PM4 andis electrically connected to the redistribution layer RDL3. In someembodiments, each of the polymer layers PM1, PM2, PM3 and PM4 includes aphoto-sensitive material such as polybenzoxazole (PBO), polyimide (PI),benzocyclobutene (BCB), a combination thereof or the like. In someembodiments, each of the redistribution layers RDL1, RDL2, RDL3 and RDL4includes conductive materials. The conductive materials include metalsuch as copper, aluminum, nickel, titanium, a combination thereof or thelike, and are formed by an electroplating process. In some embodiments,the redistribution layers RDL1, RDL2, RDL3 and RDL4 respectivelyincludes a seed layer (not shown) and a metal layer formed thereon (notshown). The seed layer may be a metal seed layer such as a copper seedlayer. In some embodiments, the seed layer includes a first metal layersuch as a titanium layer and a second metal layer such as a copper layerover the first metal layer. The metal layer may be copper or othersuitable metals. In some embodiments, the redistribution layers RDL1,RDL1, RDL3 and RDL4 respectively includes a plurality of vias and aplurality of traces connected to each other. The vias connects thetraces, and the traces are respectively located on the polymer layersPM1, PM2, PM3 and PM4, and are respectively extending on the top surfaceof the polymer layers PM1, PM2, PM3 and PM4.

In some embodiments, the topmost redistribution layer RDL4 includes RDL4a and RDL4 b. The redistribution layer RDL4 a is also referred asunder-ball metallurgy (UBM) layer for ball mounting. The redistributionlayer RDL4 b may be micro bump for connecting to an integrated passivedevice (IPD) 70 formed in the subsequent process.

Thereafter, a plurality of connectors 80 are formed over andelectrically connected to the redistribution layer RDL4 a of the RDLstructure 60. In some embodiments, the connectors 80 are made of aconductive material with low resistivity, such as Sn, Pb, Ag, Cu, Ni, Bior an alloy thereof, and are formed by a suitable process such asevaporation, plating, ball drop, or screen printing. The IPD 70 isoptionally formed over and electrically connected to the redistributionlayer RDL4 b of the RDL structure 60 through the solder bumps 72. TheIPD 70 may be a capacitor, a resistor, an inductor or the like, or acombination thereof. The number of the IPD 70 is not limited to that isshown in FIG. 5E, but may be adjusted according to the design of theproduct. An underfill layer 74 is formed between the IPD 70 and thepolymer layer PM4, and surrounds and covers the exposed RDL4 b, thesolder bumps 72 and the bottom surface of the IPD 70. After forming theconnectors 80 and the IPD 70, an integrated fan-out (InFO) packagestructure P1 is accomplished. In some embodiments, the InFO packagestructure P1 is de-bonded from the carrier 20 and is further bonded ontoa circuit substrate by the connectors 80, so as to form an integratedfan-out-on-Substrate (InFO-on-Substrate) structure.

According to some embodiments, an integrated fan-out (InFO) packagestructure including a first die, a second die, a third die, a protectivelayer, and an interconnect structure is provided. The first die has afirst surface and a second surface opposite to each other. The first diehas a plurality of through substrate vias (TSVs) protruding from thesecond surface. The second die and the third die are bonded on the firstsurface of the first die. The protective layer laterally surroundsprotrusions of the plurality of TSVs that protrude from the secondsurface. The interconnect structure are disposed on the protective layerand electrically connected to the plurality of TSVs. The interconnectstructure includes a polymer layer covering the protective layer.

According to some embodiments, a method is provided to include:providing a first die having a first surface and a second surfaceopposite to each other, wherein the first die has a plurality of throughsubstrate vias (TSVs); bonding a second die and a third die on the firstsurface of the first die; forming a first encapsulant to encapsulatingthe second and third dies, wherein the first encapsulant has a sidewallconcave from a sidewall of the first die; grinding the first die, sothat protrusions of the plurality of TSVs protrude from the secondsurface of the first die; performing an atomic layer deposition (ALD)process to form a protective layer on the sidewall of the firstencapsulant, the sidewall and the second surface of the first die, andthe protrusions of the plurality of TSVs; and performing a planarizationprocess, so that top surfaces of the protrusions of the plurality ofTSVs are coplanar with a top surface of the protective layer.

According to some embodiments, a method is provided to include: forminga package on a carrier; performing an atomic layer deposition (ALD)process to form a protective layer on a top surface and a sidewall ofthe package; performing a planarization process to expose a plurality ofthrough substrate vias (TSVs) of the package at the top surface of thepackage; forming a polymer layer on the plurality of TSVs and theprotective layer; patterning the polymer layer when the sidewall of thepackage is covered with the protective layer, so as to form a pluralityof openings in the polymer layer; and forming a conductive feature inthe plurality of openings to electrically connect the plurality of TSVs.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method, comprising: providing a first diehaving a first surface and a second surface opposite to each other,wherein the first die has a plurality of through substrate vias (TSVs);bonding a second die and a third die on the first surface of the firstdie; forming a first encapsulant to encapsulating the second and thirddies, wherein the first encapsulant has a sidewall concave from asidewall of the first die; grinding the first die, so that protrusionsof the plurality of TSVs protrude from the second surface of the firstdie; performing an atomic layer deposition (ALD) process to form aprotective layer on the sidewall of the first encapsulant, the sidewalland the second surface of the first die, and the protrusions of theplurality of TSVs; and performing a planarization process, so that topsurfaces of the protrusions of the plurality of TSVs are coplanar with atop surface of the protective layer.
 2. The method of claim 1, whereinafter performing the planarization process, the protective layercomprises: a first portion, laterally surrounding the protrusions of theplurality of TSVs and having a first thickness; and a second portion,covering the sidewalls of the first encapsulant and first die, andhaving a second thickness, wherein the second thickness is greater thanthe first thickness.
 3. The method of claim 1, further comprising:forming a polymer layer on the top surfaces of the protrusions and theprotective layer; patterning the polymer layer when the sidewall of thefirst encapsulant is covered with the protective layer, so as to form aplurality of openings in the polymer layer; and forming a conductivefeature in the plurality of openings to electrically connect theplurality of TSVs.
 4. The method of claim 3, wherein the protectivelayer and the polymer layer have different materials, and the protectivelayer has a density greater than a density of the polymer layer.
 5. Themethod of claim 1, wherein the protective layer comprises an inorganicdielectric material, and the inorganic dielectric material comprisesSiN, SiO, AlO, AlN, or a combination thereof.
 6. The method of claim 1,wherein the second and third dies have active surfaces toward the firstsurface of the first die, and the second and third dies are bonded tothe first die by a direct bonding.
 7. The method of claim 1, wherein thesecond and third dies have non-active surfaces toward the first surfaceof the first die, and the second and third dies are bonded to the firstdie by an adhesive layer.
 8. A method, comprising: forming a package ona carrier; performing an atomic layer deposition (ALD) process to form aprotective layer on a top surface and a sidewall of the package;performing a planarization process to expose a plurality of throughsubstrate vias (TSVs) of the package at the top surface of the package,wherein the protective layer laterally surrounds and directly contactsprotrusions of the plurality of TSVs after performing the planarizationprocess; forming a polymer layer on the plurality of TSVs and theprotective layer; patterning the polymer layer when the sidewall of thepackage is covered with the protective layer, so as to form a pluralityof openings in the polymer layer; and forming a conductive feature inthe plurality of openings to electrically connect the plurality of TSVs.9. The method of claim 8, wherein the package comprises: a first die,having a first surface and a second surface opposite to each other,wherein the plurality of TSVs protruding from the second surface; asecond die and a third die, bonding on the first surface of the firstdie; and a first encapsulant, encapsulating the second and third dies,wherein a sidewall of the first encapsulant is concave from a sidewallof the first die.
 10. The method of claim 9, further comprising:singulating the package, so that the sidewall of the first encapsulantis aligned with the sidewall of the first die; placing a singulatedpackage and a fourth die in parallel on a first redistribution layer(RDL) structure; forming a second encapsulant to laterally encapsulatingthe singulated package and the fourth die; and forming a second RDLstructure on the singulated package and the fourth die, so that thesingulated package, the fourth die, and the second encapsulant aresandwiched between the first and second RDL structures.
 11. The methodof claim 10, further comprising: forming a plurality of throughinsulator vias (TIVs) to penetrate through the second encapsulant andelectrically connect the first and second RDL structures; and forming aplurality of connectors on the second RDL structure.
 12. The method ofclaim 8, wherein the protective layer comprises an inorganic dielectricmaterial, and the inorganic dielectric material comprises SiN, SiO, AlO,AlN, or a combination thereof.
 13. A method, comprising: providing afirst die having a first surface and a second surface opposite to eachother, wherein the first die has a plurality of through substrate vias(TSVs); bonding a second die and a third die on the first surface of thefirst die; forming a first encapsulant to encapsulating the second andthird dies; grinding the first die, so that protrusions of the pluralityof TSVs protrude from the second surface of the first die; performing anatomic layer deposition (ALD) process to form a protective layeroverlying the sidewall of the first encapsulant, the sidewall and thesecond surface of the first die, and the protrusions of the plurality ofTSVs; and performing a planarization process to remove a portion of theprotective layer, so that top surfaces of the protrusions of theplurality of TSVs are exposed, wherein a first portion of the protectivelayer laterally surrounds the protrusions of the plurality of TSVs, anda second portion of the protective layer covers the sidewalls of thefirst encapsulant and first die.
 14. The method of claim 13, wherein thetop surfaces of the protrusions of the plurality of TSVs are coplanarwith a top surface of the first portion of the protective layer.
 15. Themethod of claim 13, wherein the first portion of the protective layerhas a first thickness, the second portion of the protective layer has asecond thickness, and the second thickness is greater than the firstthickness.
 16. The method of claim 13, further comprising: forming apolymer layer on the top surfaces of the protrusions and the protectivelayer; patterning the polymer layer when the sidewall of the firstencapsulant is covered with the protective layer, so as to form aplurality of openings in the polymer layer; and forming a conductivefeature in the plurality of openings to electrically connect theplurality of TSVs.
 17. The method of claim 16, wherein the protectivelayer and the polymer layer have different materials, and the protectivelayer has a density greater than a density of the polymer layer.
 18. Themethod of claim 13, wherein the protective layer comprises an inorganicdielectric material, and the inorganic dielectric material comprisesSiN, SiO, AlO, MN, or a combination thereof.
 19. The method of claim 13,wherein the second and third dies have active surfaces toward the firstsurface of the first die, and the second and third dies are bonded tothe first die by a direct bonding.
 20. The method of claim 13, whereinthe second and third dies have non-active surfaces toward the firstsurface of the first die, and the second and third dies are bonded tothe first die by an adhesive layer.